Field of the Invention
The present invention relates to hardware expanding device, and in particular to a data storage expanding apparatus in a server or computer system.
Description of Related Art
Reference is made to FIG. 1, which is a block diagram of a conventional data storage expanding apparatus. The data storage expanding apparatus 10 is electrically connected to and between a terminal equipment 20 (e.g. a server or computer system) and a plurality of data storage groups 30. The data storage groups 30 include a plurality of data storage devices 32 electrically connected in series. The data storage expanding apparatus 10 is configured to transmit an operation/data signal back and forth from the terminal equipment 20 to at least one data storage device 32 of the data storage group 30 electrically connected thereto. The data storage expanding apparatus 10 includes a data storage expanding module 12 and a signal expanding component 14. The data storage expanding module 12 is electrically connected to the terminal equipment 20 and the signal expanding component 14. The signal expanding component 14 is electrically connected to the data storage groups 30 such that the operating/data signal back and forth from the terminal equipment 20 can be transmitted to at least one data storage device 32 via the data storage expanding module 12 and the signal expanding component 14.
As known in the skilled of the art, the data storage expanding module 12 can be implemented by a host controller, host adapter, or host bus adapter (HBA) for the purpose of connecting a host system (e.g. the terminal equipment 20) to other storage devices (i.e. data storage devices 32 or data storage group 30). The terms “data storage expanding module 12” herein are primarily used to refer to devices for connecting SCSI, Fiber Channel or eSATA devices, as well as IDE, Ethernet, FireWire, or USB. Further, the signal expanding component 14 is utilized for facilitate communication between large numbers of storage devices, such as Serial Attached SCSI (SAS), Serial ATA, PCI, or IDE storage drive. It is also been known as the “hard disk drive expander” to form part of a service delivery subsystem and facilitate communication between storage devices (i.e. data storage devices 32 or data storage group 30), and also to facilitate the connection of multiple SAS End devices to a single initiator port (i.e. data storage expanding module 12).
It is also well known in the art that a signal expanding component 14 is only able to connect limit number of storage devices. For instance, one hard disk drive expander in the current industry practice may be able to connect twenty-four storage devices. In order to effectively transmit the data signal sent from the terminal equipment 20 to the newly added data storage devices 32 when the number of the data storage group 30 is added, additional data storage expanding apparatus 10 must be simultaneously added, and the additional data storage expanding apparatus 10 is electrically connected to the newly added data storage devices 32 and the terminal equipment 20. A data storage expanding module 12 of the additional data storage expanding apparatus 10 is electrically connected to the terminal equipment 20, and a signal expanding component 14 of the additional data storage expanding apparatus 10 is electrically connected to the data storage expanding module 12 and the data storage group 30 having newly added data storage devices 32. According to the description mentioned above, a data storage expanding apparatus 12 and a signal expanding component 14 (namely a data storage expanding apparatus 10) must be added while a data storage group 30 is added. The new added data storage expanding module 12 and the signal expanding component 14 for new the added data storage group 30 are then electrically connected to the original data storage expanding modules 12 and the signal expanding components 14 of original data storage groups 30 in parallel. After that, the operating data signal back or forth from the terminal equipment 20 can be transmitted to/between the particular data storage device 32 of additional data storage group 30. As mentioned, the capacity for signal expanding component 14 to connect the data storage devices 32 is limited. While there are more data storage devices 32 than a data storage expanding apparatus 10 could afford, an additional data storage expanding apparatus 10 has to be added into the system to absorb extra capacity of data storage devices 32. Further, the cost for a data storage expanding module 12 is much higher than a signal expanding component 14. In the current practice of structure of data storage expanding apparatus 10, one signal expanding component 14 is corresponding to one the data storage expanding module 12. The increasing number of data storage expanding apparatus 10 inevitable increases the number of the data storage expanding module 12. As such, how to reduce the number of the data storage expanding module 12 (which reduce the total cost of data storage expanding apparatus 10) and, in the meanwhile, remaining same high-speed performance become a critical issue in the related art.